Electron gun for evaporating or sublimating material in a vacuum environment



219- 121 MTRM 3,379,819 ATING MEHT A. L. HOUDE HON GUN FOR EVAPORATINGOR SUBLIM 4 Sheets-Sheet 1 I N V E NTOR. 4.051%; A. Ham;

wry/m6? A. 1.. HOUDE 3,379,819 ELECTRON GUN FOR EVAPORATING ORSUBLIMATING MATERIAL IN A VACUUM ENVIRONMENT 4 Sheets-Sheet 2 April 23,1968

Filed Sept. 15, 1966 INVENTOR.

April 23, 1968 A. L HOUDE 3,379,819

ELECTRON GUN FOH EVAPORATING OR SUBLIMATING MATERIAL IN A VACUUMENVIRONMENT Filed Sept. 15, 1966 4 Sheets-Sheet 5 April 23, 1968 A.HOUDE 3,379,819

ELECTRON GUN FOR BV APORATING OR SUBLIMATING MATERIAL IN AVACUUMIENVIRONMENT Filed Sept. 15, 1966 4 Sheets-Sheet 4 United StatesPatent Ofiice 3,379,819 Patented Apr. 23, 1968 3,379,819 ELECTRON GUNFOR EVAPORATING R SUBLIMATING MATERIAL IN A VACU- UM ENVIRONMENT AdeloreL. Houde, Garden Grove, Calif., assignor to Filmtech Associates, Inc.,Garden Grove, Calif., a corporation of California Filed Sept. 15, 1966,Ser. No. 579,678 12 Claims. (Cl. 1331) This invention relates toelectron guns of the type used in evaporating or sublimating materialsfor microelectronic thin film devices.

Electron guns are used for the evaporation or sublimation of source orevaporant material in a vacuum environment. The evaporated material istypically applied to form thin films on substrates. Thin film depositionof various materials on substrates finds application in microelectronicdevices and in such fields as magnetics and optical filters.

Electron guns operate on the theory of electron emission from a filamentor other source of electrons. A source material to be evaporated orSublimated is placed in electron communication with a source ofelectrons and bombarded. The bombardment causes the materialsevaporation or sublimation. To aid in evaporation, electrons areaccelerated from their source to the evaporant material by a largevoltage gradient which is established between the two.

It is desirable for an electron gun to be able to evaporate as manymaterials as possible in order to accommodate the many applicationspresented to thin film technology. Thus, an electron gun should becapable of evaporating such evaporants as metals, alloys, dielectricsand semi-conductors at a satisfactory and controllable rate. Moreover,in many thin film applications it is desirable to evaporate differentmaterials at the same time to produce a blend of the differentmaterials. Alternately, different distinct films of different materialmay be desired on the same substrate. In the latter instance, it wouldbe highly desirable to produce the different film without disrupting thevacuum environment in which deposition takes place. In other words, ifthe vacuum environment were destroyed for each material deposited ongiven substrate, which would be required if the electron gun had to berecharged with different evaporant materials, total production time anddeposition cost would be materially increased. Even if a commonevaporant were to be used on a given application, it may be desirable toevaporate a large quantity of the material from a single loading of theelectron gun. Because of the different applications and materials to beevaporated, an electron gun having the capacity to evaporate materialsin many forms is a very versatile instrument; thus, evaporant materialshould be able to be evaporated when it is in rod, wire, ribbon,granular or powder form.

The vacuum environment in which material deposition normally takes placeis within a bell jar. Bell jars are connected to a base plate through afeed-through ring or collar. A versatile electron gun, then, should beadapted for use with a conventional feed-through collar. In addition,provision against contamination of the electron guns electron sourceenhances the reliability, accuracy, and operating time of the electrongun; accordingly, shielding of the electron source is desirable.

It is to the accommodation of the above criteria that the instantinvention is directed. In general, the electron gun of the presentinvention includes a body, at least one electron source assembly carriedby the body, an evaporant assembly carried by the body and capable ofholding a plurality of evaporant materials, and means for selectivelypositioning the evaporant assembly with respect to the electron sourceassembly to present a given evaporant material thereto. The body isadapted to be mounted on the outside of a vacuum chamber, such as a belljar, preferably on a conventional feed-through ring. The electron sourceassembly is adapted to mount at least one filament which acts as asource of electrons. The evaporant assembly is adapted to mount aplurality of spaced-apart evaporant materials, which may be similar ordissimilar, in position to cooperate with a filament mounted in theelectron source assembly for the electron bombardment of a given one ofthe evaporant materials. The means for selectively positioning theevaporant assembly with respect to the electron source assembly allows achoice of which of the evaporant materials will be presented forevaporation. The electron source assembly and the evaporant assembly areadapted for placement within the vacuum chamber.

In preferred form, the electron gun of the present inventioncontemplates an evaporant assembly composed of a plurality of tandemlydisposed turrets. Each of the turrets has provision for the mounting ofevaporant materials at regular intervals about its radial periphery. Theturrets, as an assembly, are secured to a cylindrical support memberwhich extends into and through an axial cylindrical bore in the body.The body member has a mounting collar or flange disposed in position formounting on a conventional feed-through collar and a cylindrical portionextending normal to the mounting collar. Disposed about the outer radialsurface of the cylindrical portion of the body member are a plurality oflongitudinal grooves. These grooves are spaced apart to correspond tothe distance between evaporant materials mounted on a given turret. Abarrel is coaxially mounted around the cylindrical portion of the bodysuch that it is capable of rotational and translational movement withrespect to the body. The barrel contains a detent which provides apositive locking action when it encounters one of the longitudinalgrooves. The locking action is overcome by simply rotating the barrelwith respect to the body until a new groove is found. The barrel iskeyed to the support member such that the latters movement is mirroredby the movement of the barrel. Translational positioning of evaporantmaterials mounted on the turrets is readily accomplished through theprovision of a plurality of spaced-apart circumferential grooves On theinner cylindrical surface of the barrel. A lug operable from outside thevacuum chamber is placed in the body for selective engagement with thecircumferential slots. These slots are spaced to correspond to thetranslational position of evaporant materials mounted on the turrets.Thus by simply moving the barrel with respect to the body in bothtranslation and rotation, the position of the evaporant materialsdisposed about the radial periphery of the turrets can be adjusted. Thelocking provided in both translation and rotation occurs only whenevaporant material is in proper relationship with the electron sourceassembly for evaporation.

The electron source assemby of the preferred embodiment of the instantinvention includes a filament housing. The filament housing is adaptedto contain at least one filament in electron communication with anelectron chamber disposed within the housing. The electron chamber iscapable of being positioned such that an evaporant material mounted on aturret can extend into the chamber. The filament housing is carried by ayoke assembly which is carried by the body and adapted to extend withinthe vacuum chamber. In order to facilitate the positioning of evaporantmaterial with respect to the electron source assembly, the latter ispivotally mounted to the body to allow the clearance of evaporantmaterial from the electron chamber when it is desired to place a newevaporant material within the chamber. This pivotal action isaccomplished through a handle mounted on the outside of the body andconnected to the yoke assembly.

Among the advantages inherent in the instant electron gun is thefacility for mounting a great number of evaporant materials within avacuum chamber together with the ease of placing any one of theseevaporant materials in position for its evaporation or sublimation. Thisfacility allows a broad range of evaporants to be used withoutdisrupting the vacuum environment of deposition. If the electron gun isadapted with more than one electron source assembly, blending ofevaporant materials is possible. Moreover, because of the large numberof evaporant materials which can be mounted on the electron gunsevaporant assembly and readily positioned with respect to the electronsource assembly, a large amount of material can be evaporated withoutdestroying the vacuum in the vacuum chamber. In addition, a broadselection of evaporant materials is possible which may take any numberof forms such as rod, ribbon, wire, granular or powdered, and still beeffectively evaporated by the instant electron gun because of the easeof mounting such materials on or to the evaporant assembly. The electrongun can be readily used with existing feed-through rings and bell jars.Moreover, filament shielding is effectively and simply accomplished aswill be apparent subsequently.

These and other features, aspects and advantages of the instantinvention will become more apparent from the following description anddrawings, in which:

FIGURE 1 is an abbreviated plan view, partly in section, of a preferredembodiment of the instant invention;

FIGURE 2 is an elevational view in section taken along lines 2-2 ofFIGURE 1;

FIGURE 3 is an end view of the embodiment shown in FIGURE 1 taken alonglines 3-3;

FIGURE 4 is a side view of the embodiment shown in FIGURE 1 taken alonglines 4-4;

FIGURE 5 is an end view of the embodiment shown in FIGURE 1 taken alonglines 5-5; and

FIGURE 6 is an electrical schematic of the power system which may beused with the illustrated embodiment of the instant invention.

Referring now to the figures, there is seen the preferred electron gun 1of the instant invention. The electron gun I is adapted to be mounted ona feed-through collar 2 of standard, commercially available design foruse with, for example, a vacuum bell jar (not shown). Mounting isconveniently accomplished through the provision of a rectangularmounting collar or flange 3 with a plurality of fastener-receiving holes156. An O-ring 4 is disposed in flange 3 to provide a seal against thefeed-through ring. In general, the interior of the vacuum bell jar willsee yoke assembly '31, filament assembly support 36, filament assemblies43 and 46, and evaporant material assembly 92. In use, the outside ofthe vacuum system will see the body 8 together with attendantpositioning structure which will be described subsequently.

Yoke assembly 31 is pivotally mounted to body 8 through shaft 6 and yokesecuring pin 28. Shaft 6 is journaled in body 8 in bore 73 and has apair of annularly disposed O-rings 7 which serve as seals. On theoutside of shaft 6 is mounted a positioning lever assembly 5 which isused for pivoting yoke assembly 31 and its carried structure. As seen inFIGURE 3, positioning lever 5 comprises an arm 150 which is permanentlysecured to body 8 and rotatably receives shaft 6. Movable arm 151 issecured to shaft 6 and acts as a lever for turning shaft 6 and tiltingyoke assembly 31. Tension spring 152 is attached to lever 151 throughspring keeper 153 at one of its ends and to permanent arm 150 at itsother end. Spring 152 serves to urge the shaft 6 to the position whichkeeps yoke assembly 31 disposed in its proper relationship with respectto evaporant assembly 92 when evaporation is desired. This position isshown in FIGURE 2. Shaft 6 is connected to arm 64 of yoke assembly 31through pin 69 which is received between the tines of fork 68 formed atthe end of shaft 6. Seals 7, as well as other seals to be described, arepumped down through ducts 155 which are in vacuum communication withshaft 6 and water jacket 16. Fittings for the pump-down equipment can beconveniently placed in female threads 154. Yoke securing pin 28 isthreaded in body 8 and has a narrow portion which extends into bore 72for pivotal receipt by arm 29 of yoke assembly 31. Arm 64 as well as arm29 are received in body 8 in rectangular slots 66 and 71. These armspass through feed-through collar 2 through its opening 65. Yoke assembly31 includes an annular flange 33 which is connected to retaining ring 35by fasteners 32 and insulators 34.

Retaining ring 35 is electrically insulated from flange 33 by electricalinsulators 34 to avoid grounding of the electrical circuit used tocreate electron emission for evaporating evaporant materials mounted inevaporant assembly 92. The yoke assembly 31 has an open interior 70 inorder to accommodate water jacket and support member 16 which isdisposed coaxially with yoke 31 in body 8.

Filament assembly support 36 in general comprises a pair of arms 62 and38 which are connected to retaining ring 35 by fasteners 63 and 39. Arms62 and 38 support filament assembly 43 by a dowel connection with thefilament assemblys bosses 42. Insulator mounting member 37 is held inplaw by arms 62 and 38 and supports electrical insulators 40 and 61 aswell as terminals 41 and 60.

Filament assembly 43 as well as its associated assembly 46 are carriedby filament assembly support 36 and ultimately yoke assembly 31. In use,only one filament assembly such as that shown by reference numeral 43 inFIGURE 2 may be desired. On the other hand, additional filamentassemblies may be required which are merely added in back-to-backfasihon as shown by the attached assemblies 43 and 46 in FIGURE 1.Filament assembly 43 includes mounting bosses 42 which are secured toarms 62 and 38. Depending from these bosses is the main body portion 50which contains filament bores 56 and 52, electron chamber and filaments51 and 57. Filament bores 56 and 52 contain filaments 51 and 57 whichact as a source of electrons. Undercuts 53 and 58 communicate thefilaments with electron chamber 55 which is centrally disposed withinmain body portion 50. Each of the filaments are retained in place infilament assembly 43 as shown. The undercuts 53 and 58 have floors 54and 59 which serve to shield filaments 51 and 57 from evaporantmaterials. In like fashion filament assembly 46 includes bosses 48 fromwhich depends the mian body portion 45 of the filament assembly.Centrally disposed within assembly 46 is an electron chamber 49. Toinsure adequate shielding for the filaments contained within each of theassemblies, a shield similar to that shown by reference numeral 47 inFIGURES 1 and 2 is mounted on top of each of the assemblies. Forpurposes of clarity, one of the shields has been omitted from FIGURE 1.The shield serves to completely enclose the filaments, except to theirassociated electron chambers, from evaporant material.

Body 8 is adapted to be mounted on the outside of the feed-throughcollar or ring 2 and has an annular O-ring to seal the interior of thevacuum system from the exterior environment. Cylindrical portion 11 ofbody 8 depends normally from mounting flange 3 and has an axial bore forreceiving water jacket and support member 16. Coaxially disposed aboutcylindrical portion 11 is barrel 9. Barrel 9 is disposed to rotate aboutcylindrical portion 11 as well as translate along its length.

Translational positioning and locking of evaporant assembly 92 withrespect to filament assembly 43 is accomplished by barrel 9. Theinterior cylindrical surface of barrel 9 contains a plurality of annularspaced-apart slots 12. Each slot corresponds to the position of one ofthe turrets of evaporant material assembly 92. Lug shaft 24 is keyed tolug 21 which has an engaging rib 22 sized to fit into each of the slots12 and to lock the barrel 9 relative to the body 8 and, as will becomeapparent, evaporant assembly 92 with respect to filament assembly 43.

Spring 23, which is retained in transverse bore 159 in cylindricalportion 11 of body 8, urges lug 21 against the inside cylindricalsurface of barrel 9. Shaft 24 is keyed to positioning arm 27 by pin 26.Stop pin 157 is mounted in cylindrical portion 11 of body 8 to contactthe edges of hole 158 of lug 21 to properly position the lug in eitherits locked or unlocked state. Freeing barrel 9 for translationalmovement is accomplished by simply moving arm 27 in a clockwisedirection which releases rib 22 from any one of the slots 12.

Translation of evaporant material assembly 92 follows similar movementof barrel 9 by virtue of the latters connection to water jacket andsupport member 16 by pin 13. Pin 13 passes transversely through closingpiece 14 to its terminus in annular V-shaped groove 18 in plug andmanifold piece 17.

Rotational positioning of evaporant material assembly 92 with respect tofilament assembly 43 is accomplished by the connection of barrel 9 towater jacket 16 by pin 13. Correct rotational positioning is produced bya plurality of longitudinal peripheral grooves 129 in cylinder portion11 of body 8. Each of the grooves 129 corresponds in position to one ofthe evaporant material sockets in the turrets of evaporant materialassembly 92 when such socket is coaxially disposed within electronchamber 55 of filament assembly 43. Rotational locking is securedthrough detent ball 128 which is disposed in locking cooperation withone of the grooves 129. Detent ball 128 is urged into one of the grooves129 or the surface of cylindrical portion 11 by spring 127. Spring 127is held in place by set screw 125 which is secured in barrel 9. Detentball 128 can be forced out of one of the grooves 129 by rotating thebarrel 9. Upon finding a different one of the grooves 129, the barrel asWell as the evaporant assembly 92 will be locked in a new position.

Water jacket 16 serves as a supporting member for evaporant assembly 92and is coaxially disposed for rotation and translation within body 8.Annular seals 67 and 25, mounted in body 8, are in contact with theperipheral cylindrical surface of water jacket 16 to insure the vacuumintegrity of the vacuum enclosure. Jacket 16 is capped by plug andmanifold piece 17 which is rotatably secured within the bore of jacket16. The annular groove 18 allows movement of jacket 16 with barrel 9through pin 13 without disturbing the rotational position of plug 17.Plug 17 is rotatably positioned in jacket 16 and is sealed therein byO-ring 15. Thus, complicated water manifolding is avoided and simplemanifolding can be provided through coolant inlet fitting threads 130and coolant outlet fitting threads 132. Coolant inlet is providedthrough duct 131 and bore 104 in coolant distribution tube 20. Coolantdistribution tube 20 is secured to plug 17 and opens into inlet coolantbore 105 in cylindrical plug 106 at its other end. Cylindrical plug 106is rotatably mounted in jacket 16 and is sealed through the provision ofannular O-rings 109 and 110. Bore 105 is in coolant communication withcoolant nozzles 112 which are radially disposed in distribution tube116. Coolant outlet is provided through return ooolant passages 103 and107, the interior of jacket 16 outside of distribution tube 20, andcoolant duct 133 in plug 17.

As shown in FIGURE 2, the evaporant assembly 92 preferably comprises aplurality of tandemly-connected turrets. Each turret will have acooperating annular groove or slot 12 in barrel 9 for its translationalpositioning and locking with respect to one of the filament assemblies.Turret 100 is connected to jacket 16 by set screws 102 and 108 such thatit mirrors the movement of jacket 16 produced by barrel 9. The interiorof turret 100 includes an annular coolant groove 99 which is in thedirect path of coolant being discharged through nozzles 112. A pluralityof evaporant sockets or recesses, such as those shown by referencenumerals 98 and 114 are disposed about the radial periphery of turret100. Each of these recesses is capable of accepting and securing asource of evaporant material such as that shown in red form by referencenumeral 113 contained within evaporant socket or recess 114. Turret 93is connected to turret and has an annular coolant groove 95, an annularcoolant bore 96, as well as a plurality of evaporant sockets such asthose shown by reference numerals 94 and 115. Closing piece 90 isthreaded to turret 93 and sealed by O-ring 91 to prevent the passage ofcoolant into the interior of the vacuum system. Each of the evaporantsockets of each of the turrets has a cooperating longitudinal groove 129on the cylindrical portion of body 8 for its correct radial positioningrelative to the evaporant assemblies. In addition, the evaporant socketsof each turret are radially aligned with corresponding sockets in otherturrets in order that proper radial positioning of evaporant materialswith respect to the filament assemblies can be accomplished by a commonone of the longitudinal grooves 129.

The electrical system preferred for dual evaporation with the electrongun 1 of the instant invention is shown schematically in FIGURE 6. Thissystem envisions the use of low voltage alternating current for heatingthe filaments. Superimposed on the alternating current is a negativevoltage which is applied to the filaments to create a large voltagegradient between the evaporant materials and the filaments. Thisgradient is possible because the evaporant assembly is at groundpotential while the electron emitting filaments contained within thefilament assemblies are at a high negative voltage. The differential involtage, then, will accomplish a direction of electrons to evaporantmaterials contained on the evaporant assembly and disposed within theelectron chambers of the filament assemblies to cause their evaporationor sublimation.

Alternating current source is connected to primary winding 171 oftransformer 173. The secondary winding 172 of transformer 173 isconnected at one of its ends to junction 183. The other end of secondarywinding 172 is in series circuit with filaments 174 and 175 and meetsthe first end of secondary winding 172. at junction 183. A complementaryalternating current power source 186 is connected to primary winding 185of transformer 187. The secondary winding 184 of transformer 187 isconnected at one of its ends to junction 183 and is serially connectedat its other end to filaments 177 and 178. The alternating currentcircuit of transformer 187 is completed through junctions 176 and 181 atjunction 183. Thus, the secondary windings of transformers 173 and 187are tied at junction 183. A high voltage source 179 has its positiveterminal 182 connected to ground while its negative terminal 180 isconnected to junction 181. Junction 181 is connected to junction 176 andthus filaments 177, 178, 174 and 175 are in circuit with high voltagesource 179 through secondary windings 172 and 184 to junction 183.

The circuit illustrated in FIGURE 6 would be applied to the electron gun1 shown in FIGURE 1 as follows: Filaments 174 and 175 would correspondto filaments 51 and 57. The circuit between filaments 51 and 57 iscompleted by main body portion 50 of filament assembly 43. Either of theterminals 41 or 60 would correspond to junction 176 while the otherterminal would carry the lead to secondary 172. Filaments 177 and 178would be secured in filament assembly 46. Filament 178 would beconnected to the terminal corresponding to junction 176 while filament177 would be connected directly to secondary winding 184.

If only one filament assembly is desired, one of the alternating currentpower supplies would be eliminated from the circuit shown in FIGURE 6.In this case, filaments 51 and 57 of FIGURE 1 would correspond tofilaments 174 and 175 of FIGURE 6. The serial connection between thesetwo filaments is provided by the main body portion 50 of filamentassembly 43. One of the terminals 41 or 60 would be connected tosecondary winding 172 and each would be connected to one of thefilaments. The other of the terminals 41 or 60 would be connected tohigh voltage source 179 and to the other end of secondary winding 172.

In use, the electron gun I is mounted on feed-through ring 2 after anyof a number of selected evaporant materials inserted in the evaporantsockets, such as are shown on FIGURE 2 by reference numerals 98, 94, 115and 114. These evaporant materials maybe of similar or dissimilarmaterials. The vacuum environment for evaporation or sublimation is thensecured. A selected one of the evaporants is positioned relative to thefilament assembly 43 such that it extends into the electron chamber 55for electron communication with filaments 51 and 57. The evaporant sodisposed is then subjected to electron bombardment for any desiredpurpose.

If another evaporant material is desired to be evaporated by theelectron gun within electron chamber 55, yoke assembly 31 together withfilament assembly 43 are pivoted upwardly by positioning lever assembly5. This frees electron chamber 55 from evaporant material 113 or anyundesired evaporant material which may pass underneath it. While theyoke 31 and filament assembly 43 are in the raised condition, a newevaporant material may be placed for evaporation. If the desiredevaporant material is located on a turret translationally removed fromfilament assembly 43, for example turret 93, then handle 27 is moved ina clockwise direction against the urging of spring 23 to free rib 22 oflug 21 from one of the circumferential slots 12. Barrel 9 is then pulledoutward and handle 27 released allowing rib 22 to find the next adjacentslot. The translational position of turret 93 with respect to filamentassembly 43 is then correct. Radial positioning is adjusted by simplyrotating the barrel 9 in either a clockwise or a counterclockwisedirection which frees detent 128 from the longitudinal groove 129 inwhich it is disposed. When a subsequent longitudinal slot is encounteredby detent 128, an evaporant material will be disposed in properrelationship to the filament assembly 43. If the radial position of thedesired evaporant is more than one place removed, then as many of thelongitudinal slots 129 as are required are bypassed.

Simultaneous evaporation or sublimation of evaporant materials containedwithin evaporant assembly 92 is of course possible. Because the radialand translational positions of each of the turrets are accurate, thepositioning of one evaporant material with respect to one filamentassembly will automatically position a corresponding evaporant materialwith respect to a second fiilament assembly. In short, the turrets aresized with respect to the tandemly oriented filament assemblies, such asshown in FIGURE 1, to provide the proper simultaneous disposition ofevaporants within the fiilament assemblies electron chambers.

The coolant of the turrets and evaporant material contained therein isreadily accomplished through the passage of coolant through bore 104,duct 105, the hollow interior of member 116, and nozzles or jets 112.The coolant will impinge upon the annular grooves 99 and 95 of turrets93 and 100, respectively. Because of the reduced heat path provided atthe base of the evaporant socket or recess, maximum cooling isaccomplished. Coolant return, as has been previously described, isaccomplished through coolant passages 107 and 103 disposed within plug106, the interior of jacket 16 between distribution tube 20 and thejackets inner wall, and out through duct 133.

What is claimed is:

1. An electron gun for use in evaporating material in a vacuum chambercomprising:

(a) a body adapted to be mounted on the outside of the vacuum chamber;

(b) at least one electron source assembly carried by the body forplacement within the vacuum chamber, each electron source assemblyhaving at least one filament capable of emitting electrons upon thepassage of electric current through the filament;

(c) an evaporant assembly carried by the body for placement within thevacuum chamber and adapted to mount a plurality of spaced-apartevaporant materials, the evaporant assembly being capable of cooperatingwith the filament of each electron source assembly to expose a selectedone of the evaporant materials to such filament for evaporation; and

(d) means for selectively positioning the evaporant assembly withrespect to each of the electron source assemblies to expose any selectedone of the evaporant materials to the filament of such assembly.

2. The electron gun claimed in claim 1, wherein the evaporant assemblyincludes at least one turret, each of the turrets being adapted to mounta plurality of spacedapart evaporant materials around its radialperiphery.

3. The electron gun claimed in claim 2, wherein each of the electronsource assemblies includes a filament housing, each filament housinghaving an electron chamber capable of receiving at least a portion of aselected one of the evaporant materials, and at least a portion of thefilament of each electron source assembly being disposed in itsassociated filament housing such that electron communication betweensuch filament and such selected one of the evaporant materials ispossible.

4. The electron gun claimed in claim 3, wherein the selectivepositioning means includes means for raising the filament housings withrespect to the evaporant assembly such that each electron chamber may bedisposed above the evaporant material.

5. The electron gun claimed in claim 4, wherein the selectivepositioning means includes means for rotating the turrets about theirlongitudinal axes.

6. The electron gun claimed in claim 5, wherein the selectivepositioning means includes means for translating the turrets along theirlongitudinal axes.

7. The electron gun claimed in claim 6, including:

(a) locking means operable to lock the turrets against rotation upon therotational positioning of an evaporant material at least substantiallycoaxial with one of the electron chambers;

(b) locking means for locking the turrets against translation upon thetranslational positioning of an evaporant material at leastsubstantially coaxial with one of the electron chambers; and

(c) means to release the translational and rotational locking means.

8. An electron gun for use in evaporating material in a vacuum chambercomprising:

(a) a body having a mounting collar for securing the body on the outsideof the vacuum chamber;

(b) a yoke assembly pivotally mounted to the body and adapted to extendinto the vacuum chamber; (c) at least one filament assembly carried bythe yoke assembly, the filament assembly including an electron chamberand means for mounting at least one filament in electron communicationwith the electron chamber;

(d) a turret assembly carried by the body and adapted to extend into thevacuum chamber, the turret assembly having at least one turret, theturret including a plurality of means for mounting evaporant materialsaround its radial periphery such that a single evaporant material at atime is capable of being received in the electron chamber;

(e) means for selectively positioning the turret assembly with respectto the filament assembly to expose any desired one of evaporantmaterials mounted in the turret to electron bombardment; and

(f) means on the body operable from outside the vacuum chamber forraising and lowering the yoke assembly about its pivot.

9. The electron gun claimed in claim 8, wherein the body includes:

a cylindrical portion disposed normal to the mounting collar and anaxial cylindrical bore extending through the cylindrical portion and themounting collar; the turret assembly including;

a cylindrical turret support member rotatably and slidably carried bythe body in its axial cylindrical bore and capable of extending into thevacuum chamber, the turret support member carrying the turrets; and

the selective positioning means cooperates with the turret supportmember such that the turrets are positionable through the support memberin both translation and rotation.

10. The electron gun claimed in claim 9, wherein the selectivepositioning means include a barrel, the barrel being rotatably andslidably mounted to the body around its cylindrical portion, and theturret support member being keyed to the barrel for movement therewith.

11. The electron gun claimed in claim 10, including:

(a) rotational locking means for fixing the rotational position of anevaporant material mounted on the turret;

(b) translational locking means for fixing the transla tional positionof an evaporant material mounted on the turret; and wherein (c) therotational and translational locking means are operable by the selectivepositioning means.

12. The electron gun claimed in claim 11, wherein:

(a) the rotational locking means includes a plurality of longitudinallyspaced-apart grooves in the cylindrical surface of the cylindricalportion of the body, each groove corresponding to the rotationalposition of one of the evaporant material mounting means, and a detentmounted in the barrel in locking communication with the grooves; and

(b) the translational locking means includes a lug rotatably mounted inthe body, a plurality of circumferentially spaced-apart slots in theinner surface of the barrel, each slot corresponding to thetranslational position of one of the evaporant material mounting means,the lug being capable of engaging one of the slots at a time.

References Cited UNITED STATES PATENTS 3,303,320 2/1967 Miller l331 XRROBERT K, SCHAEFER, Primary Examiner.

M. GINSBURG, Assistant Examiner.

1. AN ELECTRON GUN FOR USE IN EVAPORATING MATERIAL IN A VACUUM CHAMBERCOMPRISING: (A) A BODY ADAPTED TO BE MOUNTED ON THE OUTSIDE OF THEVACUUM CHAMBER; (B) AT LEAST ONE ELECTRON SOURCE ASSEMBLY CARRIED BY THEBODY FOR PLACEMENT WITHIN THE VACUUM CHAMBER, EACH ELECTRON SOURCEASSEMBLY HAVING AT LEAST ONE FILAMENT CAPABLE OF EMITTING ELECTRONS UPONTHE PASSAGE OF ELECTRIC CURRENT THROUGH THE FILAMENT;